1. Field of the Invention
The present invention relates to a printer for forming an image on a paper sheet such as a thermal recording paper which is colored by heat.
2. Description of the Related Art
In a field of a printer forming an image on a paper sheet, a thermal recording paper which is colored by heat is conventionally used. In a printer using the thermal recording paper, the thermal recording paper is generally contained in an airtight paper container, since the thermal recording paper has a behavior easily be deteriorated by humidity. The paper container is generally comprised of a base member mounted on a housing of a printer and a cover member rotatably pivoted by a pair of hinges on the base member. The thermal recording paper is contained in an inner space formed by the base member and the cover member as a roll.
As for the hinges of the conventional paper container, a pair of bearing portions each having a horizontal center hole is formed on one of the base member or the cover member, a pair of or two pairs of bearing portions is or are formed on the other of the base member or the cover member, and a pair of hinge pins serving as rotation shafts of the hinge structures is provided for penetrating through the center holes of the bearing portions. For preventing the escape of the hinge pins from the center holes of the bearing portions, independent members such as E-shaped rings are used. The E-shaped ring, however, is generally difficult to be engaged with the hinge pins, since a working space between the base member and the cover member is narrower. In other words, the conventional hinge structure of the conventional paper container is designed regardless of the assemble workability.
With respect to the hinge structure of the container, Japanese Laid-Open Patent Application No. 2000-73643 shows that a hook with a guide slit and an engaging protrusion is integrally formed on an end of a hinge pin, and a flange engaged with the guide slit and engaging recesses engaged with the engaging protrusion are formed on an outer face in the vicinity of the hinge. When the hinge pin is inserted into center holes of bearing portions of the hinge, the guide slit is engaged with the flange and the engaging protrusion is engaged with one of the engaging recesses, so that it is possible to prevent the escape of the hinge pin.
Furthermore, Japanese Laid-Open Patent Application No. 5-59864 shows a hinge pin having a larger diameter portion adjoining to a portion to be inserted into center holes of bearing portions of a hinge, and a stopper is formed to be contacted with the larger diameter portion, so that it is possible to prevent the escape of the hinge pin.